@janine
I don’t quite understand，Where is the KHR materials unlit extension？
The default material I should use。
enabling “Generate Smooth Normals” did not improve the problem。
@Kevin_Ring
I used 02_CesiumMelbourne and still found the problem
Is it the unity version? My version is 2021.3.7
Other than that(unrelated to this question),I used my own modified material in the problem before, and the detection Normals failed, but enabling "Generate Smooth Normals has solved the snow I made.